In this application, the term earpiece—including the term “ear mold” (sometimes expressed as the closed compound word “earmold”)—refers to any device placed into the outer ear for purposes of affecting hearing—whether by enhancement (e.g., a hearing aid, an earphone, audio headphones) or by reduction (e.g., protection against loud sounds such as would be experienced in the vicinity of guns, aircraft engines, concerts, etc.). Such purposes include effects on hearing which are not performed by the earpiece per se; for example, a stethoscope (acoustical or electronic) which employs earpieces as described below for its eartips is within the scope of this application. Other applications include cell phone communication (e.g., Bluetooth™ or other wireless protocols, or wired connection); wired or wireless computer, radio, TV, iPod®, iPad®, and other similar types of audio listening (including consumer, professional, and “audiophile” applications); and in general any application in which there is a need for better fitting appliances for the outer ear for reasons of comfort, lasting fit, or both.
The hearing health care field and consumer electronic industry have long pursued without success a viable, single-physical-size earpiece. Numerous standard fitting earpieces have been advocated to house hearing devices or communication devices or to be used with them, respectively. To date, few of these have proven to provide a satisfactory universal fit. There are always some ears on which these devices do not fit properly, resulting in ear irritation and/or acoustic feedback produced by the lack of an adequate acoustic seal of the ear canal, occlusion problems or poor retention in the ear. For example, poorly-fitting earpieces are one of the main causes for a large percentage of hearing aids being returned or not being used.
Some of these poor-fit problems are caused by the unforgiving, hard, incompressible acrylic material used to house the electronic components. The difficulty applies to either custom or standard earpieces and occurs when the wearer speaks or chews, exercises, or moves, any of which causes the ear canal to change shape significantly, thus causing an earpiece to no longer fit well. The result at these times of jaw movement is a poorly-fitting earpiece that causes the earpiece to fall out or allow slit leakage to occur, which produces acoustic feedback and is uncomfortable to wear because it irritates the wearer's outer ear.
Numerous attempts have been made to solve the jaw moving-poorly fitting earmold/earpiece problem. For example, U.S. Pat. No. 6,434,248 B1 describes a custom in-the-ear type hearing aid made with a soft shell that conforms to the wearer's ear canal as jaw motion occurred. The soft shell encapsulates the electronic components of the hearing aid and is bonded to a hard faceplate. While this approach provides a theoretical improvement over a hard-shell hearing device, difficulties were encountered in trying to reliably adhere the shell to the faceplate, and, in practice, the two parts often separated. In addition, the soft shell materials tend to tear apart and the wires often break.
Universally-fitting or standard size earpieces were developed in the hearing industry for a number of reasons: product cost and time for device delivery were reduced because there was no longer a two to three week wait between the time at which the ear impression was taken and delivery of a custom hearing aid. A proper universal fitting hearing device requires less follow-up care for the wearer, translating into less time in the hearing professional's office trying to solve fit problems, resulting in greater satisfaction with hearing devices.
There have been numerous attempts at developing and manufacturing standard fitting earpieces. For example, U.S. Pat. No. 6,205,227 describes a standard fit hearing device with a rigid shell and hollow, deformable tip. The problem with this device was that the rigid shell was too large for some ears, and the flexible tip was either too large or too small for some ears, both problems resulting in an unacceptably low successful fitting rate. U.S. Pat. No. 6,097,825 describes a hearing aid packaged in standardized spheroidal housings having predetermined curvatures corresponding to that of typical ear canals. The problem with this approach was that there were many ear canals whose curvature did not correspond with those of the spheroidal housings. In another example, U.S. Pat. No. 5,002,151 describes a soft, disposable sleeve in several standard lengths that has threads which screw onto mating threads on an earpiece. The problem with this assembly was that a combination of the foam tip and earpiece was too long for most ear canals, resulting in the earpiece sticking out of the wearer's ear.